Catalysts are used in motor vehicles with combustion engines to clean pollutants, above all nitrogen oxides, out of the exhaust gas. For this purpose, the exhaust gas is passed through a catalyst body, in which the pollutants are deposited. In order to achieve a sufficient gas-cleaning action, the catalyst body must have a certain minimum temperature. As this minimum temperature is not immediately ready, for example, after a cold start, it is usual to heat the catalysts electrically. In this way, the cold-start behavior of a motor vehicle can be shortened and pollutants in the exhaust gas can thereby be reliably eliminated.
In this case, for heating purposes, electrodes are provided on a shell surface of a catalyst body. As these electrodes stick out laterally from the catalyst, however, they make it more difficult to install a housing around the catalyst body.